I'm running 302 heads on my straight LPG 351 and was wondering what you guys recommend for spark plugs. I'm currently using an NGK (one colder then stock), with a smaller gap after reading the following article.
NGK's comments . . .
To eliminate the influence of L.P.G. and to obtain optimum spark plug performance, NGK recommends:
-The use of a spark plug with one heat range colder (if possible) than that listed in the catalogue: eg, BPR6EFS-13 (L.P.G.) instead of BPR5EFS-13 (petrol) for VN 6 Cylinder Commodore.
-The reduction of the electrode gap by 0.1 mm (which lowers the spark plug required voltage)
(SOURCE = http://www.ngkspark.com.au/bulletin_T92-1.htm
I can't find the article now, but a guy recommended grinding half of the electrode away to better expose the flame front to the charge. It's a delicate operation, but I think it helped.
Anybody tried Iridium plugs? That small tip doesn't look as though it will give much of a spark, but I know looks are quite deceiving.